The Mental Lives of Zombies

This week, I’m blogging about my new book, The Epistemic Role of Consciousness (Oxford University Press, September 2019). Thanks to John Schwenkler for hosting me. Today, I’ll start by situating the project of the book within a broader landscape in the philosophy of mind.

What is the role of phenomenal consciousness in our mental lives? To make this question vivid, let’s consider a thought experiment. Imagine that when you wake up one morning, you have become what philosophers like to call a zombie: that is, an unconscious creature with no capacity for conscious experience. When you get out of bed and make breakfast, there is nothing it is like for you to taste your coffee, to see the sun shining outside, or to think through your plans for the day.

Of course, we cannot imagine this scenario from the inside, since there is nothing it is like to be a zombie, but we can still imagine it from the outside. And we can imagine that you continue to look and act just the same as normal. From the outside, nothing has changed. The absence of consciousness is no impediment to your prospects for survival and reproduction. It has no impact on your personal hygiene or your professional responsibilities. You get through the day just fine. It is just that your daily activities are now conducted without any associated experience.

All this seems perfectly conceivable. We can imagine it easily enough. It is a contested question whether the conceivability of zombies implies that they are really possible, but we can set that aside here. The point of the thought experiment is not to raise metaphysical questions about the nature of consciousness and its place in the physical world. Instead, the goal is to raise a question about the significance of consciousness. If we become zombies, are we thereby guaranteed to lose anything of significance?

In one way, the answer seems obvious. Consciousness matters. The prospect of losing consciousness forever is quite terrifying. It wouldn’t feel bad, of course, but it wouldn’t feel good either. In losing consciousness, we thereby lose something that makes life worth living. A life without consciousness seems massively impoverished. Indeed, it’s tempting to say that such a life would be entirely meaningless. None of us, I assume, would choose to become zombies even given the assurance that it would not impair our conduct in any observable way. This suggests that consciousness has intrinsic value: it matters for its own sake and not just for the instrumental benefits it can bring (Siewert 1998: Ch. 9).

My book is not concerned with the intrinsic value of consciousness, however, but rather with its role in our mental lives. If you become a zombie, how much of your mental life are you thereby guaranteed to lose? By stipulation, you would lose conscious experience. But what implications does this have for your other mental capacities for representing, reasoning, and knowing about the external world?

In Chapter 1: Consciousness, I distinguish three broad theoretical perspectives on the role of consciousness in our mental lives. One view is bifurcationism. On this view there are two distinct concepts of mind: the phenomenal concept of mind as conscious experience and the psychological concept of mind as the causal basis of behavior (Chalmers 1996: Ch. 1). Since these concepts are distinct, it is conceivable that they can come apart. For example, while zombies have no phenomenal states, they can still have psychological states that are functionally defined by their causal role in producing behavior. On this view, zombies might retain their capacity for mental representation, reasoning, and knowledge without any capacity for phenomenal consciousness. Hence, phenomenal consciousness has no indispensable role to play in our psychological lives. We can excise phenomenal consciousness while leaving our psychological lives more or less intact.

Bifurcationism contrasts with unificationism, which says that there is a conceptual connection between phenomenal and psychological concepts of mind. But the nature of this connection is disputed: some proponents of unificationism argue that we should analyze phenomenal consciousness in terms of its psychological functions, while others argue that we should analyze psychological functions in terms of phenomenal consciousness. Let’s consider these options in turn.

One version of unificationism puts psychological functions first. On this view, phenomenal consciousness is analyzed in terms of its psychological role in action, cognition, or metacognition, where these psychological roles can be functionally defined in purely causal terms. This view has the implausible consequence that the zombie scenario can be ruled out on conceptual grounds, since anything that duplicates the causal structure of my psychology thereby duplicates my phenomenal life too. If this is guaranteed on conceptual grounds, then it is inconceivable that I might lose phenomenal consciousness without this making any causal impact on my psychology. And yet this seems perfectly conceivable. That doesn’t mean there is no conceptual connection between phenomenal and psychological concepts of mind, but it does suggest that the direction of analysis should be reversed.

Another version of unificationism puts phenomenal consciousness first. This view holds that phenomenal consciousness is our most basic concept of mind and that other psychological concepts, such as mental representation, cognition, and knowledge, are analyzed in terms of their connections with phenomenal consciousness. On this view, it’s perfectly conceivable that we could become zombies, but it’s inconceivable that we could lose phenomenal consciousness while leaving our psychological lives wholly intact. Hence, phenomenal consciousness plays an essential role in our psychology.

My main goal in the first half of the book is to develop a version of the research program in philosophy of mind that puts phenomenal consciousness first. Many others have also pursued this “consciousness-first” program, but what makes my version distinctive is its appeal to the epistemic role of consciousness. In Chapter 2: Representation, I distinguish three versions of the consciousness-first program and explain how my version is distinctive.

One version of this program says that all mental representation is grounded in consciousness. On this view, zombies cannot represent the world, since consciousness is the basis of all mental representation. I argue against this view on broadly empirical grounds. The key point is that unconscious mental representation plays an indispensable explanatory role in commonsense psychology and scientific psychology alike. On this view, zombies can have mental representations that play an indispensable role in explaining their behavior.

Another version of this program says that all conceptual thought is grounded in consciousness. On this view, perhaps zombies can represent the world, but they cannot think about the world. I argue that the epistemic role of consciousness is more fundamental than the role of consciousness in thought. We can explain the role of consciousness in thought by appealing to the epistemic role of consciousness together with epistemic constraints on conceptual thought.

My own version of the consciousness-first program says that all epistemic justification is grounded in consciousness. On this view, zombies have no epistemic justification to form beliefs about the world around them and so they cannot know anything about the world. Moreover, this epistemological claim has consequences for the philosophy of mind. After all, perception and belief are psychological states that provide epistemic justification to form beliefs about the world. Hence, zombies cannot perceive the world, and they cannot believe anything about the world. Their psychological lives are radically different from our own.

The book is divided into two parts. The first part of the book explores various different aspects of the epistemic role of consciousness in our mental lives, while the second part develops a unified epistemology in which consciousness plays a central role. Over the next three days, I will discuss the epistemic role of consciousness in connection with perception, cognition, and introspection. On Friday, I will explain how I integrate these claims about the epistemic role of consciousness into a unified theory of epistemic justification.